public class String {

    public static void main(String[] args) {

        StringBuilder sb1 = new StringBuilder("hello");
        StringBuilder sb2 = sb1;
        System.out.println(sb1.reverse());
        System.out.println(sb1.append(" "));
        System.out.println(sb1.append("world"));
        System.out.println(sb1.append(123));
        System.out.println(sb1);
        System.out.println(sb1 == sb2);
        System.out.println(sb1.charAt(0));
        System.out.println(sb1.length());
        System.out.println(sb1.capacity());
        sb1.setCharAt(0, 'H');
        System.out.println(sb1);
        System.out.println(sb1.insert(0, "Hello world"));
        System.out.println(sb1.indexOf("Hello"));
        System.out.println(sb1.lastIndexOf("Hello"));
        System.out.println(sb1.deleteCharAt(0));
        System.out.println(sb1.delete(0, 5));

        System.out.println(sb1.substring(0, 5));
        System.out.println(sb1.toString());



    }
}
